A typical fire suppression device comprises a cannister of pressurized fire suppression material and a valve. The fire suppression material in the cannister may include a propellant, if necessary, to discharge the fire suppression material. The valve has an outlet port through which suppression material from the cannister is discharged. The valve typically has a valve member or piston which moves inside a central chamber between a closed position, in which the suppression material is prevented from reaching the outlet port, and a closed position, in which the suppression material is released. The piston is normally latched in the closed position to resist a pressure force from the pressurized suppression material. The latch may be selectively released, allowing the pressure on the piston to displace it, opening the discharge port which it had blocked.
Fire suppression devices are often used in limited space environments. The interior of the Bradley fighting vehicle, for example, is relatively compact and has a designated amount of space dedicated for storing fire suppression devices. It is, however, desirable for the device to store as much fire suppression material as possible in the given space. This is particularly so in the military application where advanced sensors can trigger highly responsive extinguishers to provide important life-saving functionality.
Conventional fire suppression devices do not maximize the amount of suppression material contained in a given space. In order to meet space limitations, it will be appreciated that the size of the cannister is reduced by the profile height of the valve. Previous devices have pistons which actuate in a vertical direction, aligned with the cannister. As a result, considerable vertical space is taken up by the valve, thereby reducing cannister height and, consequently, volume of suppression material available.
Furthermore, fire suppression valves typically use a pressure force created by the pressurized suppression material to actuate the piston from the closed to the open position. More specifically, previous fire suppression devices often releasably lock the piston in the closed position so that a piston end of the piston blocks an outlet passage to prevent discharge of suppression material. A trigger mechanism is then used to release the lock, thereby allowing the pressure force of the pressurized suppression material to actuate the valve mechanism to an open position. Therefore, in conventional, vertically oriented valves, the piston end not only prevents flow of suppression material in the closed position, but also provides an actuating surface against which the pressure force acts to move the piston to the open position.
Certain conventional fire suppression valves also fail to adequately seal the valve against leakage of low molecular weight propellant. In the closed position, the valve member must seal with the outlet passage to reliably prevent propellant from escaping over extended periods of time. It will be appreciated, however, that materials having lower molecular weights are capable of escaping through relatively small gaps in the valve. As a result, when a valve is used with a sole propellant such as nitrogen gas, which has a relatively low molecular weight of 28 when compared to other fire suppression materials like Halon 1301, having a molecular weight of 148.9, the piston must form a tight seal with the outlet port. Unfortunately, some conventional valves are not reliably formed with adequate seal compression.
It is also desirable to reuse components of the fire suppression device after the suppression material is discharged. Reuse of the valve, without the need for replacing expensive components, can be particularly significant in military applications, where the devices are discharged fairly frequently. It is more difficult, however, to reuse a valve through which dry powder has been discharged. In such applications, the interior of the valve is covered with dry powder particles. The particles are known to disrupt the internal seals of the valve, thereby facilitating leakage of suppression material. While attempts may be made to clean the inside of the valves, such as with pressurized air, it is not certain that all powder particles will be removed. Furthermore, more thorough cleaning often requires a significant amount of valve disassembly.